Advantech PCM-3753I, User Manual

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PCM-3753I User Manual 16
If the jumper JP1 is enabled and the initial configuration is caused by a
reset, all ports will return to the states they had just prior to the reset. The
reset must be a "hot" reset (power not disconnected) for enabled JP1 to
return ports to their prior values. Otherwise, the card behaves as though
JP1 were not enabled. Please refer to "Jumper settings" in Chapter 2 for
more information.
3.2.5 Dry Contact Support for Digital Input
Each digital input channel accepts either dry contact or 0 ~ 5 VDC wet
contact inputs. Dry contact capability allows the channel to respond to
changes in external circuitry (e.g., the closing of a switch in the external
circuitry) when no voltage is present in the external circuit. Figure 3-1
shows external circuitry with both wet and dry contact components,
connected as an input source to one of the card's digital input channels.
Figure 3.1: Wet and Dry Contact Inputs
Note For wet contact configurations, a malfunction
may occur if the internal resistance of the voltage
source is significant (> 1.5 kW). It is advisable to
connect a 1.5 kW resistor in parallel with such a
voltage source to avoid a voltage rise inside the
voltage source.
1.5 K Ω
0.5 W
PC 5V
10 K
Ω
Buffer
Dry Contact: Open High
Close Low
Wet Contact: 2.0~5.25 V
DC
High
0~0.8 V
DC
Low
External Internal
Resistor
in
Parallel